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Methylamine and dimethylamine photocatalytic degradation—Adsorption isotherms and kinetics

Paper ID Volume ID Publish Year Pages File Format Full-Text
41257 45882 2011 7 PDF Available
Title
Methylamine and dimethylamine photocatalytic degradation—Adsorption isotherms and kinetics
Abstract

The photocatalytic degradation of two nitrogenous organic compounds, methylamine CH3NH2 and dimethylamine (CH3)2NH, used in pharmaceutical and chemical industries was investigated in the presence of UV-irradiated TiO2 aqueous suspensions. Different parameters were studied: adsorption under dark and UV-A conditions, photolysis, kinetics of degradation, and chemical pathway of methylamine (MA) and dimethylamine (DMA) degradation. The percentage of covered OH in the dark was equal for different concentrations of MA and DMA. The adsorption isotherms of these two amine compounds MA and DMA follow the Langmuir model. The photocatalytic oxidation kinetics of MA and DMA are described by the Langmuir–Hinshelwood model with a first order kinetics for concentrations below 0.5 mmol L−1, and then reach a plateau.For both MA and DMA, the coverage rates of the TiO2 surface in the dark and under illuminated conditions were different. The nitrogen atoms were decomposed mainly to ammonium (NH4+). Nitrite (NO2−) was also formed but was rapidly oxidized to nitrate (NO3−). MA was detected as an intermediate product during the degradation of DMA. Formic acid (HCOOH), and two other products not identified were detected. These non-identified products do not correspond to formamide. Total Organic Carbon (TOC) analysis shows the presence of final slightly mineralised intermediate compounds.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (81 K)Download as PowerPoint slideHighlights► Same area density (molecule nm−2) of adsorbed MA and DMA are obtained. ► The higher reactivity of MA than DMA is due to the higher reactivity of the cationic form. ► The breaking of C–N bond is the main initial step in the degradation of DMA. ► For MA and DMA, the coverage rates of the TiO2 in dark and under UV were different.

Keywords
Adsorption; Dimethylamine; Methylamine; Photocatalytic degradation; TiO2
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Methylamine and dimethylamine photocatalytic degradation—Adsorption isotherms and kinetics
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 402, Issues 1–2, 31 July 2011, Pages 201–207
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
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Any Questions? feel free to contact us